Objective： Studies have shown that TNF- α secreted by tumor ceils and macrophages infiltrated into the tumor microenvironment might promote the metastasis of a variety of malignant cancers, including breast cancer. The present study was designed to detect global metastasis-related gene expression changes of MCF-7 cells treated by low dose TNF-α and to further explore the mechanisms by which TNF- α contributes to metastasis. Methods： MCF-7 cells were cultured and treated with low dose TNF-α （20 ng/ml）, cDNA array analysis was applied to detect the metastasis related gene expressions. Results： A total of 36 gene expressions were significantly regulated by TNF- α. Functional analysis indicates that the altered genes belong to different functional group. Most of the genes changed may promote the metastasis of MCF-7 cells while the others may inhibit metastasis. The changes observed in gene expression following TNF-α were somewhat time dependent. Conclusion： TNF-α can enhance the invasive ability of MCF-7 cells, partly by regulating a series of metastasis related genes, and these genes may take part in every step of metastasis. Some of the genes deserve further study.
